Resuscitator



United States Patent [72] Inventor Roger E. W. Manely Amersham, England [2]] Appl. No. 670,158 [22] Filed Sept. 25, 1967 [45] Patented Dec. 15, 1970 [73] Assignee Blease Medical Equipment Limited Chesham, England [32] Priority Oct. 3, 1966 [33] Great Britain [31] No. 44058/66 [54] RESUSCITATOR 6 Claims, 4 Drawing Figs.

[52] US. Cl 128/1453 [51] Int. Cl. A62b 7/00 [50] Field ofSearch... 128/142- [56] References Cited UNITED STATES PATENTS 4,014 7/1870 Andrews 222/522 Primary Examiner-Richard C. Pinkham Assistant Examiner-Theatrice Brown Attorney- Fleit, Gipple & Jacobson ABSTRACT: A portable resuscitator for handheld use, for example for sufferers from respiratory troubles has a constant volume chamber with an inlet and a iarger outlet, closed by an exit valve. The exit valve is triggered in response to pressure changes in the chamber. The chamber may exhaust into a second chamber which encloses the triggering mechanism. The second chamber may have an inhalation/exhalation valve in its wall.

PATENIED DEL! 519m Q SHEET 1 OF 2 INVENTOR- Y Md M M R 2 9 rr/ s.

RESUSCITATOR This invention relates to resuscitators.

An aim of the invention is to provide a compact resuscitator of relatively low cost and which is suitable for use as a personal resuscitator.

According to the invention, we provide a resuscitator comprising a constant volume chamber having an inlet orifice of size chosen to pass a predetermined rate of flow of gas at a predetermined inlet pressure, an outlet orifice larger than the inlet orifice, pressure-responsive means in the chamber, and an exit valve associated with the outlet orifice responsive to the said means and arranged in conjunction therewith to control the exit of gas in such a way that the exit valve is opened when the pressure within the chamber is above a first predetermined limiting value and is closed when the pressure within the chamber falls below a second predetermined value.

Illustrative embodiments of the invention will now be particularly described with reference to the accompanying drawings, in which:

FIG. 1 is a partly diagrammatic axial section through one embodiment of resuscitator omitting certain parts,

FIG. 2 is a diagrammatic representation of a toggle mechanism for effecting opening and closing of the exit valve,

FIG. 3 is a diagrammatic representation of a second embodiment of mechanism for effecting opening and closing of the exit valve, and

FIG. 4 is a diagrammatic representation of yet a further embodiment of mechanism for operating an exit valve of a different type.

The resuscitator illustrated in FIG. 1 comprises a cylindrical chamber having an upper end wall 12 in which is located an inlet orifice I4 constituted by a bore in a plug 16 mounted in the end wall 12. The orifice 14 is of a size chosen to pass a predetermined rate of flow of gas at a predetermined inlet pressure. A flexible pipe 18 is connected to the plug 16 and to a cylinder or other source of gas, for example oxygen, which constitutes the supply of gas to the resuscitator.

The cylindrical chamber 10 is bounded at its other end by a wall 20 having a central aperture 22 therein. This wall also has a plug 24 having a central bore 26 therein, this bore 26 constituting an outlet orifice for the gas in the chamber 10. The plug 24 has one of its ends formed as a valve seat 28 to cooperate with a valve member 30 of an exit valve. The valve member 30 is mounted on an arm 32 pivotally connected to a bracket 34 secured to the wall 20. The exit valve is biassed into the closed position by a tension spring 36.

A bellows 38 is secured to the wall 20 to cover the aperture 22 by a clamping ring 40 appropriately fastened to the wall 20 to make a fluid-tight connection. The bellows 38 has an end wall 42 suitably shaped to provide a spring seat for a compression spring 44 and secured to the plate 42 is a rod 46. In an alternative construction, not shown, the rod 46 may be a sliding fit in the aperture 22 in the end wall, and need not be fixed to the end plate 42.

The inlet orifice 14 is dimensioned to permit an inflow of gas at a rate of about 8 litres per minute at an inlet pressure (i.e. pressure of the supply cylinder regulator) of about 80 p.s.i. atm. The outlet orifice 26 is dimensioned to permit a gas flow out of the chamber 10 of about 32 litres per minute at an internal pressure within the chamber of about 3040 p.s.i. The internal volume of the chamber 10 is desirably about 150 cc. The purpose of the rod 46 is to actuate a mechanism that controls or effects opening and closing of the exit valve by moving the valve member 30 into or out of engagement with the valve seat 28. This mechanism is not shown on FIG. 1, and three possible alternative forms that it can take are illustrated in FIGS. 2, 3 and 4.

Continuing to refer to FIG. 1, the exit valve 28,- 30 opens into a second chamber 50 bounded at its lower end by a flexible diaphragm 52. This diaphragm carries a plate valve member 54 having a central orifice 56. The valve member 54 is adapted to cooperate with a valve seat 58 of'an exhalation valve. The valve seat 58 is formed by one end of a tube 60, which passes through the end wall 62 of the resuscitator, and

terminates in a spigot 64 to which can be attached a face mask 66 for a user of the resuscitator. An orifice 68 is provided adjacent the end wall 62 to allow gases expelled by the user of the resuscitator when breathing out to vent freely to atmosphere. It will be seen that when the user does breathe out, the increase in pressure pushes valve member 54 away from valve seat 58 allowing the expelled air to pass between these parts and out of the orifice 68.

The operation of the device so far described is as follows.

Gas to be used for resuscitation purposes enters from a cylinder or from another appropriate source continuously through pipe 18 and outlet orifice 14, at about 8 litres per minute and at the start of the cycle it is assumed that exit valve 28, 30 is held closed by tension spring 36. Pressure builds up within the chamber 10, and acts on the end plate 42 of the bellows. When the force acting on this plate exceeds the force exerted by compression spring 44, the bellows contracts and the rod 46 is pushed downwardly as seen in FIG. 1. It engages lever arm 32 and consequently valve member 30 is pushed off valve seat 28 thus opening the exit valve. This allows gas to flow through the orifice 26 into the second chamber 50, and this flow proceeds at about 32 litres per minute. In consequence the pressure within chamber 10 drops rapidly, since the outflow is very much faster than the inflow, and this pressure eventually reaches a value at which the combined forces exerted by springs 36 and 44 expand the bellows 38 and allow the exit valve to close. The gas in the second chamber 50 can pass through the orifice 56 to the tube 60, 64 and thence to the user via face mask 66. The orifice 56 is chosen to be of a sufficiently small size so as to offer an impediment to its flow and consequently a pressure is generated in the chamber 50 that causes valve member 54 to stay in contact with valve seat 58. A spring (not shown for simplicity in FIG. I) is provided to withdraw the disc 54 from contact with exhalation valve seat 58 when valve 28 closes. When the user breathes out, the spring pulls valve member 54 off the valve seat 58 allowing exhaled gas to vent to atmosphere via aperture 68 as previously described. The pressure in chamber 50 is always sufficient to provide an adequate flow through the orifice 56 to meet the needs of a users inhalation phase.

Referring now to FIG. 2, one form of mechanism by which movement of the rod 46 effects opening and closing of the exit valve 28, 30 takes the form of a toggle mechanism. This mechanism comprises a cruciform shape member mounted on a fixed pivot 82 for pivotal movement about an axis perpendicular to the axis of the cylinder 10. The member 80 is connected to the rod 46 by a link 84 and pivotal connections 86. A part 88 of the cruciform shape member 80 engages a compression spring 90 whose other end is housed in a spring cap 92 this is pivotally connected to a strap member 94 pivoted at 95 to the cruciform member 80 for limited angular movement. The parts 88, 90 constitute a toggle linkage having two rest positions, one as shown in FIG. 2 and one in which the parts 88, 90 are located on the opposite side of the centre line of the strap member 94. In one of these positions the strap member 94 is located as shown in FIG. 2 and in the other the left-hand end of the strap member moves in a downward direction in relation to the position shown in the FIG. The strap member 94 is connected by means of a link 98 and two pivots 100 to the lever arm 32 so that pivotal movement of the strap member 94 in an anticlockwise direction as seen in the drawing effects opening movement of lever arm 32 carrying exit valve member 30. It will be seen that downward movement of rod 46 causes a clockwise pivotal movement of cruciform member 80 by virtue of the connecting link 84 and consequently an anticlockwise movement of strap member 94. In consequence, upon increase in pressure in chamber 10, the exit valve 28, 30 is opened. In a similar way, upon decrease of pressure in the chamber 10 the rod 46 is moved upwardly under the influence of spring 44 expanding the bellows 38, and cruciform member 80 is moved anticlockwise and strap member 94 clockwise to restore it to the position shown in FIG. 2 in which the exit valve 28, 30 is of course closed.

Referring now to FIG. 3, in a second embodiment of mechanism for actuating the exit valve 28, 30 in response to pressure variation within the chamber 10, the rod 46 has two circumferential grooves 120, 122 at or towards its lower end. The rod size is chosen to be a sliding fit in the aperture 22 of the wall 20. The grooves 120, 122 preferably have sidewalls (e.g. 124) at about 45 to the axis of the rod 46.

The wall 20 is provided with a lateral bore 128 which houses a compression spring 132 and an adjusting screw 136. The spring 132 is stressed between adjusting screw 136 and a ball 140 of metal, for example steel, which is thereby urged into the groove 122 or 120 as the case may be.

With this construction, it will be seen that a force in the downward direction exerted on rod 46 by pressure within the chamber will cause the rod 46 to move downwardly when the force reaches a predetermined level, i.e. when a predetermined pressure is reached in the chamber 10. When the rod moves downwardly, it engages lever arm 32 and pivots it in an anticlockwise direction as seen in FIG. 3. This causes valve member 30 to leave valve seat 28 thereby opening the exit valve. The level of force required to move the rod 46 is, as will be seen, the sum of the forces exerted by compression spring 44 and the component of the force exerted by spring 132 since it is necessary for the ball 140 to be pushed back into the bore 128 before the rod 46 can move. The rod 46 moves downwardly until the ball 140 seats in the groove 120. When the pressure in chamber 10 falls to a second predetermined value, the force exerted on thetop of the bellows and the component of force exerted by the spring 132 are together insufficient to resist the force of spring 44 acting to expand the bellows. When this occurs the bellows expands, rod 46 is drawn upwardly, and the spring 36 shuts the exit valve 28, 30.

The following specific values are suitable. In the case of the embodiment shown in FIGS. 1 and 2, the springs 44 and 90 are chosen such that at a pressure of about 60 p.s.i. in the chamber 10, the exit valve is opened, and at a pressure of 7 about p.s.i. the exit valve is closed. In the embodiment illustrated by FIGS. 1 and 3, the springs 44, and 132 are chosen in size, in conjunction with the slope of the groove walls, such 1 that a similar result is obtained.

An alternative arrangement of exit valve and operating mechanism therefor is illustrated in FIG. 4, which shows a .modified form of a part of the resuscitator illustrated in FIG.

-I. In this embodiment, the wall has a circular aperture within which the rod 46 is a close sliding fit. In order to prevent escape of gas between the rod 46 and the wall 20, a

cap 150 is secured in a fluidtight manner to the lower surface of the wall 20.

The wall 20 has a lateral bore 152 within which is contained a compression spring 154. This bears at one end on a metal ball 156 and at its other end on an adjusting screw 158. The rod 46 is provided with peripheral, grooves, for example 45 grooves, 160 and 162 which are similar to the grooves 120 and 122 of FIG. 3. i

The parts are illustrated in FIG. 4 in the exit valve open" condition, i.e. when there is a pressure above a predetermined level within the chamber 10.

The rod 46 has an axial bore 164 therein, and this is extended to the exterior of the rod by a radial bore 166. The wall 20 has a lateral bore 168 connected to a-bore 170 by which the bore 168 is connected to the second chamber 50.

It will be seen that with this construction, when the pressure in the chamber 10 falls, the spring 44 urges the rod 46 up- .wa'rdly until ball 156 engages in groove 162, and under these It will be seen that the resuscitator specifically described herein is a resuscitator embodying a new principle, in that instead of being a substantially constant-pressure variablevolume device such as is disclosed in our British Pats. Nos. l,028,934 and 1,028,935 the present device is a substantially constant-volume variable-pressure device.

The employment of this new principle brings with it considerable advantages in that the device can be made small enough to be held in the hand and in'particular the cylindrical chamber 10 can serve as a handle, and even in conjunction with a small cylinder .of compressed oxygen as the primary source, the resulting resuscitator assembly is small enough to be easily carried either on the person min a pocket in a motor car. It is anticipated that this will be of particular value to people suffering from heart or respiratory troubles, as these people will be able to have a resuscitator always ready to hand without the difficulty of transporting a large, heavy or bulky amount of equipment.

Another important feature of the resuscitator disclosed herein in that it can be constructed almost entirely from metal. for example, cast aluminum or aluminum alloy. This is of importance, especially in that rubber seals can be almost entirely dispensed with. As will be appreciated, a resuscitator should have a very long shelf life and even after many years without being used, must of necessity be able to function perfectly when required. It has been found that deterioration of rubber seals and the like inexisting forms of resuscitator has had a depressing influence on the speed of their introduction to the market.

With the specific dimensions disclosed herein, the ratio of the period of inspiration to the period'of expiration is approximately 1:3 which is in good accordance with the ratio currently thought desirable for resuscitation purposes by the medical profession. Another feature of the resuscitator disclosed herein is that it is well suited for connection to existing standard hospital pipeline supplies of oxygen, since the standard pressure available from such pipeline is of the order of I00 p.s.i.

Iclaim: I

l. A resuscitator comprising: a constant volume chamber having an inlet orifice of the size sufficient to pass a predetermined rate of gas at a predetermined inlet pressure; an outlet orifice larger than said inlet orifice; pressure responsive means in said chamber; an exit valve containing said outlet orifice, the said exit valve being responsive to the said pressure responsive means and arranged in conjunction therewith to control the exit of gas in such a way that the exit valve is opened when the pressure within the chamber is above a first predetermined limiting value and is closed when the pressure within the chamber falls below a second predetermined value; a second chamber having a common wall with the constant volume chamber, the outlet orifice being disposed in the said common wall; a flexible diaphragm bounding the second chamber on one of its sides; a valve member carried by said flexible diaphragm, said valve member defining a permanently open orifice therein through which orifice in use, gas supplied to the second chamber via the exit valve can pass to a user; and a valve seat adjacent said diaphragm externally of said chamber, the said valve member and valve seat constituting an exhalation valve.

2. A resuscitator according to claim 1 in which the exit valve is formed by the cooperation of a rod whose movement is controlled by the pressure responsive means and which has a central bore, with a bore in one of the walls of the chamber, the bore of the rod registering with the bore in the wall in the open condition of the exit valve, and in which a spring loaded detent is provided to maintain the rod in its condition cor.- responding to the open condition of the exit valve.

3. A resuscitator according to claim 1 in which said pressure responsive means is a bellows which acts upon a central rod which can effect opening or closing of the exit valve as the case may be, the rod having two stable positions, one corresponding to the open condition of the exit valve and the positions, one such position corresponding to the open condition of the exit valve and the other to its closed condition.

6. A resuscitator according to claim 5 in which the toggle mechanism is such as to open the exit valve at a pressure internally of the chamber greater than about p.s.i. atm. and to close it at a pressure less than about 15 p.s.i. atm. 

